The propulsion system found on heavy-duty vehicles as well as on tracked recreational vehicles such as snowmobiles for example comprises longitudinally spaced apart wheel structures driven by an endless, substantially inextensible belt having an inner surface and an outer surface. The inner surface is provided with a series of longitudinally spaced members for guiding the track relative to driving and tracking wheels forming part of the wheel structures. The outer surface of the belt is formed of a plurality of longitudinally spaced tread members that provide traction to the vehicle when travelling on various ground conditions.
The wheel structures typically comprise a driven wheel and an idler wheel, with a series of supporting mid-rollers.
The endless belt engages the necessary supporting wheels such as drive and idler wheels or rollers. A recurrent problem relates to the wear out of the mid-rollers.
Typically, the mid-rollers are made of steel and protected with a layer of rubber, which proves to have a chunking problem and an overall reduced lifetime as well as providing a limited protection efficiency against rocks penetration to the track. Another solution also contemplated is the use of steel scrapers to clean off any debris so as to prevent them to be ingested between the track inner surface and support surfaces of the wheels of the improved wheel structure.
U.S. Pat. No. 6,299,264 discloses a solution for protecting the mid-rollers of an endless track laying work machine by a heat shield positioned between guide blocks of the endless track and an inner shoulder of the mid-wheel.
There is still a need in the art for an improved wheel structures driven by an endless track belt.